Electrical socket connector with mercury contact



www o o c G w. L. KAclN Filed Nov. 14, 1957 ELECTRICAL SOCKET CONNECTORWITH MERCURY CONTACT May 3, 1960 INVENTOR. WILLIAM L.KAc|N BY j C?) aATTORNEY oo coco ole o o o o o a'o c o ono do o oo aoc o ELECTRICALSOCKET CONNECTOR WITH MERCURY CONTACT Wiiliam L. Kacin, Flushing, N.Y.,=assignor to Faxiniile, Inc., New York, N.Y., a corporation of DelawareApplication November 14, 1957, Serial No. 696,373

9 Claims. (Cl. 339-118) The present inventan relates to the an ofelectrical'- ployed devices including spring contacts for effecting'.

quick detachable connections to other electrical circuits. Because ofthe small area of contact available the direct electrical connectionbetween the fine wire terminal and an associated circuitthrough aconventional connection is frequently lost. This is due to carbonizationof the contacting surfaces, development of ylooseness in the springs,and other mechanical faults. A

The present invention has as its principal object the provision of aconnector which is free from spring con'- tacts and in which directelectrical connection is accortiplished'via a conductive fluid in ametal tube havingk a closed end. A further object is to provide a plugand receptacle assembly in which one or more tine wire prongs may beseated in a receptacle containing one or more bodies of conductive iiuidsuch as mercury. A further object is to provide a. receptacle containingone or more bodies of a conductive liquid, with the liquid exposed tothe exterior of the receptacle via one or more open passages. A furtherobject is to provide aconnector member in the form of a block supportinga conductive container having a body of mercury therein with the blockhaving one ormore open passages for insertion of electrical conductorsinto the body of mercury.

The other and further objects `of the invention will become apparentyfrom the following description taken together with the drawing wherein:

Fig. l is a plan View of a plug and receptacle embodying the invention.

Fig. 2 is a sectional View taken on lines v2 2 of Fig. l, with the plugand receptacle interttedgwith each other.

Fig. 3 is a sectional view on an enlarged scale of another form ofreceptacle. Y

Fig. 3A is a fragmentary sectional viewsimilar to Fig. 3 illustrating amodification of the invention. Y

Fig. 4 is a fragmentary sectional View on an enlarged scale of anintertted plug and receptacle. n

Figs. 4A and 4B fare fragmentary sectional views similar to Fig. 4employed in explaining the invention.

Fig. 5 is an end View of the receptacle shown in Fig. l.

Fig. 6 is a perspective View of the .plug shown in Fig. l.

Figs. 7 and 8 are end views of other. forms ofplug and receptaclerespectively.

Figs. 9 and 10 areA perspective views of further forms of plug andlreceptacle respectively.

Fig. 11 is a perspective view of a portion of a receptacle` illustratinga stage in the assembly thereof. v

Referring to Figs. l, 2 and 6, there is shown a plug which is formed ofa block of insulating material such as plastic, ceramic, or the like.Embedded in tlie block 21 is a. plurality of wires 22 disposed in acoplanai" parallel array. End 23 of the block is' dat. Out of this endpro'- nited tates Patent ject the terminals 24 of the wires 2.2. Theseterminals serve as prongs of the plug. The wires may be formed ofstainless steel or other material which is not wettable by theconductive uid in the connector to ybe described. Block 21 may beprovided with a pair of recesses 25 `for receiving the locating pins 26best shown in Fig. l. It is intended that the prongs 24 be inserted intothe receptacle and the portions of the wires 22 extending out of otherend of the block be connected in -a suitable elec trical circuit.-

The structure of the receptacle 30 is best shown in the Figs. 1, 2', 4and 5. The receptacle may be formed of a block 31 of insulation materialin which is seated a metal tube or container 32 having an open end 33and a closed end 34. The tube is cylindrical in form and has acylindrical cavity which contains a body 38 of a conduc= tive iuid. Thisiluid may be a liquid metal suchas mercury, gallium or other metal oralloy thereof which is liquid in form at 4the temperature at which theconnector is to be used. Secured to end 34 of the tube by means ofsolder 39 is wire 40. This wire is part of an electrical circuit towhich it is desired that oneeof wires 22 make direct electrical contact.Another block of insulation material 42 having a recess 43 is insertedover the open end of the tube, a pair of plates 50 and 5 1 hold blocks31 and 42 together ina unitary assembly. Screws 52 extend into' theblocks from the plates for assembling the connector.

in Fig. 3 is shown another form of receptacle which includes a block ofinsulation material 45. The block is provided with a bore 46 in which isseated a tube 35 containing a body of a liquid metal 38 such as mercury.Wire' 4G is attached by solder 39 to the end 34 of the tube. This endprojects out of the rear side of the Vblock so that the wire can bereadily attached thereto; Blocks 42 and 4S in Figs. 2 and 3 are eachprovided with a narrow passage 55. This passage communicates directlywith the open end 33` of the tube 35. The outer end of the passage isformed as a concave countersunk recess 56. The diameter of the open end33 of the tube is at least three times the diameter of passage 55 sothat the area of end 33 is not less than about ten times larger than thecross-sectional area of the passage 55.

When the plug is disconnected from the receptacle, the outer end of thebody of mercury 38 forms a convex meniscus 6i) near the inner end ofpassage 55. This cnvex shape of the meniscus is formed when Athe metalof tube 35 is not wetted by the mercury.` 'The tube 35 may be made ofstainless steel, chromium and other metal which does not react with theconductive iiuid. It will be noted that because of the high surfacetension existing at the open end 33 of the tube the curved meniscus ispresented by the body of mercury to the inner end, of passage 55. Thismeniscus requires a considerable force to be penetrated Or broken.Normal vibration or shaking of the connector is insufcient to break theme; niscus, and thus minute droplets of the conductiven fluid cannotpass through the passageway. The tube should be only partially lled withmercury to allow room fot', expansion of the metal due to increase inambient terri'-y pe'rature. When the prong 2.4 is inserted into the bodyof mercury as best shown in Fig. 4 a cusp 61 is fried around the prongat the point of entry in'to the liquid metal. This re-entrant shapeassumed by the meniscus at .the prong is structurally stronger than theoriginal convex shape of meniscus 69 as shown in Fig. 3. The

annuiar space S within the passage around .prong 24 is less than theprevious unoccupied space so that an even i greater resistance toleakage of the mercury through kthe passage 55 exists; e e A e It isnecessary that the crios's'sectional area of passage' 55 be slightlylarger than the diameter of prong 24 in order that the prong may freelyenter the body of mercury and to provide means for the escape of airfrom the tube as the prong is inserted therein. This space also preventsmercury being drawn out by suction when the prong is withdrawn. VTheconvexity of the meniscus around the prong 24 in Fig. 4 indicates thatthe mercury does not wet the metal of the prong which. is wetted bymercury a concave meniscus 64 is formed as shown in Fig-3A. The prongshould not be made of a metal which is wettable by mercury. lf suchmetal were used then a conical area 62 would be formed in the meniscus60 around the prong as shown in Fig. 4A, and the mercury would be drawnout of the tube 35 by the wet prong when the plug was separated from thereceptacle.

In Fig. 4B, the prong 24 is shown inserted into a concave meniscus 64formed when the tube 35 is wetted by the mercury. A cusp 61 forms aroundthe prong which is not wetted by the mercury. This curved form of themeniscus has a greater resistance to breakage than the concave form ofthe meniscus 64 so that leakage of mercury past the prong cannot takeplace in passage 55.

In Fig. 7 is shown a plug including a block 70 having prongs 24 disposedin a rectangular array. The prongs are arranged in a plurality of rows.Four recesses 25 are provided near opposite corners of the block 70 forreceiving pins 26 of the receptacle 72 which is shown in Fig. 8.Passages 55 in the receptacle are arranged to receive the prongs 24.Each passage terminates in a countersunk opening 56.

In Fig. 9 the plug block 74 carries a single prong 24 which is theterminal of wire 22. Recesses 25 in block 74 receive the two locatingpins 26 carried by receptacle 75 as shown in Fig. 10. A single passage55 is provided in receptacle 75 to receive the prongs 24. Each of thepassages 55 in receptacles 72 and 75 terminate at the openings of tubes35 in the same manner as shown in Figs. 2, 4.

Fig. 11 shows a step in the procedure for assembling the receptacle 30.Tube 35 to which wire 40 has been soldered is partially embedded inblock 31. The open end 33 of the tube is accessible for inserting of aquantity of mercury or other conductive fluid into the tube. After themercury is inserted in the tube the capping block 42 (in Fig. 2) isplaced over block 31 and then plates 50 are attached.

' In the form of the invention shown in Fig. 3 a single block 45 is usedfor the receptacle so that fastening plates 50 are not required.

The plug and receptacle block may be made of any suitable insulationmaterial such as plastic, ceramic, glass, etc. Abutting faces of theplug and receptacle blocks should be flat to fit iiush against oneanother and provide a sealed joint between the blocks. If the conductivefluid exhibits any tendency to vaporize such as might occur due toheating of the `connector during extended use, this tendency may becounteracted effectively by improving the joint between the faces. Thismay be done by coating the faces with rubber or other flexible materialto insure a hermetically sealed joint between the plug and receptacleblocks where the prongs are fully inserted into the bodies of conductiveliuid. The tubular containers 35 are preferably made of conductivematerial such as a suitable metal. They may be made of nonmetallicmaterial provided that the wires 40 are extended to pass through theends 34 to make direct electrical contact with the conductive fluidbodies 3S. It is possible Yto use other conductive fluids than liquidmercury and liquid -gallium in the tubes 35. If desired the fluid may beof any substance which has a low vapor pressure and high surface tensionso that it will not evaporate or ow through the narrow passages 55 inthe receptacles. Suitable liquids are viscous oils, polyethylene glycoland ,4 the like. The body may be rendered electrically conductive byaddition of minute particles of metal such as silver, aluminum, copper,etc. The particles should be sufliciently small to be retained inpermanent suspension in the liquid. The material of the prongs 24 mustbe so selected that they are not wetted by whatever liquid is selectedfor the fluid bodies 38.

While certain specific embodiments of the invention have been describedand illustrated by way of example, it will now be apparent to thoseskilled in the art that various modifications may be made withoutdeparting from the spirit and scope of the invention as defined in theappended claims.

What is claimed and sought to be protected by Letters Patent of theUnited States is:

1. An electrical receptacle comprising block means of insulationmaterial, said block means having a plurality of substantiallycylindrical cavities therein, a plurality of cylindrical electricallyconductive tubes disposed in the respective cavities and substantiallycompletely filling the cavities, each tube having a closed and an openend, said block means having a plurality of spaced passages thereincorresponding to the number of said cavities and extending from the openends of the respective tubes to the exterior of the block means, a bodyof liquid metal disposed in each of the tubes, the cross sectionalareaof each of the passages being less than the cross sectional area of theopen end of each tube so that the liquid metal is prevented by surfacetension from flowing through said passages if the block means is turnedto invert the tubes, and a plurality of electric conductors connected tothe closed ends of the tubes, said conductors being out of contact withsaid liquid metal to prevent contamination thereof by material of theconductors.

2. An electrical receptacle comprising block means of insulationmaterial, said block means having a plurality of substantiallycylindrical cavities therein, a plurality of cylindrical electricallyconductive tubes disposed in the respective cavities and substantiallycompletely filling the cavities, each tube having a closed and an openend, said block means having a plurality of spaced passages thereincorresponding to the number of said cavities and extending from the openends of the respective tubes to the exterior of the block means, a bodyof liquid metal disposed in each of the tubes, the cross sectional areaof each of the passages being less than the cross sectional area of theopen end of each ltube so that the liquid metal is prevented by surfacetension from flowing through said passages if the block means is turnedto invert the tubes, and a plurality of electric conductors connected tothe closed ends of the tubes, said conductors being out of contact withsaid liquid metal to prevent contamination thereof by material of theconductors, the closed ends of the tubes extending out of the blockmeans so that the connections of the conductors thereto are external ofthe block means.

3. A connector comprising an interfitting plug and a receptacle, saidplug comprising first block means of insulation material carrying aplurality of exposed metal prongs, said receptacle comprising secondblock means of insulation material having a plurality of substantiallycylindrical cavities therein, a plurality of cylindrical electricallyconductive tubes disposed in the respective cavities and substantiallycompletely filling the cavities, each tube having a closed and an openend, said second block means having a plurality of spaced passagestherein corresponding to the number of said vcavities and extending fromthe open ends of the respective tubes to the exterior of the secondblock means, ya body of liquid metal disposed in each of the tubes, thecross sectional area of each of the passages being less than the crosssectional area of the open end of each tube so that the liquid metal isprevented by surface tension from fiowing through said passages shouldthe second block means be turned to invert the tubes, and a plurality ofelectric conductors connected to the closed ends of the tubes, saidconductors being out of contact with the liquid metal to preventcontamination thereof by material of the conductors, said prongsextending through said passages into the bodies of liquid metal, themetal of said prongs being unwettable by said liquid metal.

4. A connector comprising an intertitting plug and a receptacle, saidplug comprising first block means of insulation material carrying aplurality of exposed metal prongs, said receptacle comprising secondblock means of insulation material having a plurality of substantiallycylindrical cavities therein, a plurality of cylindrical electricallyconductive tubes disposed in the respective cavities and substantiallycompletely iilling the cavities, each tube havinga closed and an openend, said second block means having a plurality of spaced passagestherein corresponding to the number of said cavities and extending fromthe open ends of the respective tubes to the exterior of the secondblock means, a body of liquid metal disposed in each of the tubes, thecross sectional area of each of the passages being less than the crosssectional area of the open end of each tube so that the liquid metal isprevented by surface tension from ilowing through said passages shouldthe second block means be turned to invert the tubes, and a plurality ofelectric conductors connected to the closed ends 0f the tubes, saidconductors being out of contact with the liquid metal to preventcontamination thereof by material of the conductors, said prongsextending through said passages into the bodies of liquid metal, themetal of said prongs being unwettable by said liquid metal, the closedends of the tubes extending out of the second block means so that theconnections of the conductors thereto are external of the second blockmeans.

5. An electrical receptacle comprising block means of insulationmaterial, said block means having a plurality of substantiallycylindrical cavitiestherein, a plurality of electrically conductivetubes disposed in the respective cavities and substantially completelyfilling thel cavities, each tube'having a closed andan open end, saidblock means having a plurality of spaced passages therein correspondingto the vvnumber of said cavities and extending from the open ends of therespective tubes to the exterior of the block means, a body of liquidmetal disposed in each of the tubes, the cross sectional area of each ofthe passages being less than the cross sectional area of the open end ofeach tube so that the liquid metal is prevented by surface tension fromliowing through said passages if the block means is turned to invert thetubes, the closed ends of the tubes extending out of the block means sothat conductors may be connected thereto.

6. A connector comprising an intertting plug and a receptacle, said plugcomprising iirst block means of insulation material carrying a pluralityof exposed metal prongs, said receptacle comprising second block meansof insulation material having a plurality of substantially cylindricalcavities therein, a plurality of cylindrical electrically conductivetubes disposed in the respective cavities and substantially completelyfilling the cavities, each tube having a closed and an open end, saidsecond block means having a plurality of spaced passagestherein'corresponding to the number of said cavities and extending fromthe open ends of the respective tubes to the exterior of the secondblock means, a body of liquid metal disposed in each of the tubes, thecross sectional area of each of the passages being less than the crosssectional area of the open end of each tube so that the liquid metal isprevented by surface tension from ilowing through said passages shouldthe second block means be turned to invert the tubes, and a plurality ofelectric conductors connected to the closed ends of the tubes, saidconductors being out of contact withy the liquid metal to preventcontamination thereof by material of the conductors, said prongsextending through said passages into the bodies of liquid metal, themetal of said prongs being unwettablc bytsaid liquid metal, there beingdirect electrical continuity between the prongs and conductors throughthe body of liquid metal and bodies of liquid metal and the tubes, saidelectrical continuity being maintained in all positions of the interttedplug and receptacle.

7. An electrical receptacle comprising block means of insulationmaterial, said block means having a plurality of substantiallycylindrical cavities therein, a plurality of cylindrical electricallyconductive tubes disposed in the respective cavities and substantiallycompletely filling the cavities, each tube having a closed and an openend, said block means having a plurality of spaced passages thereincorresponding to the number of said cavities and extending from the openends of the tubes to the exterior of the block means, a body of liquidmetal disposed in each of the tubes, the cross sectional area of each ofthe passages being less than the cross sectional area of the open end ofeach tube so that the liquid metal is prevented by surface tension fromflowing through said passages if the block means is turned to invert thetubes, and a plurality of electric conductors connected to the closedends of the tubes, said conductors being out of contact with said liquidmetal to prevent contamination thereof by material of the conductors,said block means being formed of two separable sections to facilitatedisposition of the tubes in the cavities.

8. An electrical receptacle comprising block means of insulationmaterial, said block means having at least one substantially cylindricalcavity therein, a cylindrical walled electrically conductive tubedisposed in and substantially completely iilling said cavity, said tubehaving a closed and an open end, said block means having a passagetherein extending from the open end of the tube to the exterior of theblock means, a body of liquid metal disposed in the tube, the closed endof the tube being imperforate and leak-proof, and an electric conductorconnected to the exterior of the tube so that the conductor is out ofdirect contact with the liquid metal while being in direct electriccircuittherewith through the tube, said circuit being continuous in allpositions of said block means.

9. An electrical receptacle comprising block means of insulationmaterial, said block means having at least one substantially cylindricalcavity therein, a cylindrical Walled electrically` conductive tubedisposed in and substantially completely filling said cavity, said tubehaving a closed and an open end, said block means having a passagetherein extending from the open end of the tube to the exterior oftheblock means, an electrically conductive liquid body disposed in saidtube, said body including an electrically conductive metal which extendsthroughout'said body, the closed end of the tube being imperforate andleak-proof, and an electric conductor connected to the exterior of thetube so that the cony ductor is out of direct contact Vwith said bodywhile being t in direct electric circuit therewith through the tube,said circuit being continuous in all positions of said block means. n

References Cited in the file of this patent UNITED STATES PATENTS

